1. Field of the Invention
The present invention relates to a rotor which is provided with end rings and to an electric motor.
2. Description of the Related Art
Known in the art is a rotor which is provided with end rings which short-circuit a plurality of conductors which are arranged at a rotor core, wherein reinforcing members for preventing deformation of the end rings when driving rotation of the rotor are attached to the outer circumferences of the end rings (for example, Japanese Patent Publication No. 2013-090447A).
In the above-mentioned rotor, a shaft, the end rings, and the reinforcing members are generally fabricated from different materials, so due to the difference in coefficients of thermal expansion among these members, sometimes the shaft ends up deforming at the time of operation of the rotor. According to the above patent publication, the reinforcing members are divided into a plurality of members to prevent such deformation of the shaft. However, according to this configuration, there is the problem that the number of parts which form the rotor increases and the work steps at the time of production increase, so the manufacturing cost rises.
Further, end rings easily deform when operating an electric motor at a high speed, so in the past, reinforcing members were assembled together with the end rings only in an electric motor for high speed operation use. Therefore, it had been difficult to make use of common parts for an electric motor for high speed operation use and an electric motor for low speed operation use.